Dome lights won't come on

I was installing a new car stereo, and my friend advised against disconnecting the battery. We got everything on and working, and when I went to put the stereo and the rest of the dash unit back in, I heard a pop and all the lights in the cabin of the car went out. My headlights and tail lights work, and the car starts fine. I simply don't get lights on the inside. I've searched both the inside (by the driver door) and outside (under the hood) fuse boxes for the fuse for the interior lights, but to no avail. Help!!